Method and apparatus for on-demand production of digitally imaged webs

ABSTRACT

Improved web printing and handling apparatus ( 10, 84, 88 ) is provided which includes an improved digital printing assembly ( 12 ) having a bidrectionally rotatable impression drum ( 18 ) presenting an outer surface ( 20 ), as well as at least one digital print head ( 22 ) adjacent the drum outer surface. The overall apparatus ( 10, 84, 88 ) also has a downstream web cutting and handling assembly ( 14 ) with an adhesive applicator ( 32 ), laser cutter ( 40 ) and image collection assembly ( 44 ). In use, a web ( 16 ) traverses the drum ( 18 ) with essentially no relative movement between the web ( 16 ) and drum surface ( 20 ), and the print head(s) ( 22 ) are actuated to form individual images on the web ( 16 ). Thereafter, the printed web passes into and through the assembly ( 14 ) where adhesive is applied and the individual images are laser cut and collected using assembly ( 44 ).

RELATED APPLICATION

[0001] This is a continuation of U.S. patent application Ser. No.09/852,531, filed May 9, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is broadly concerned with web printing andhandling apparatus, and corresponding methods, wherein images areindividually printed on a continuous web using a relatively largerotating impression drum and associated digital print heads; thereafter,the printed web passes through a downstream cutting and handlingassembly where the individual printed images are laser cut andcollected. More particularly, the invention is concerned with suchapparatus and methods wherein use an improved drum/digital print headprinting assembly which permits high speed, on-demand production ofimages for labels or the like, using relatively inexpensive, thin,lightweight webs.

[0004] 2. Description of the Prior Art

[0005] Traditionally, pressure sensitive labels have been produced usingmore or less standard, multiple-tower web-fed printing apparatusfollowed by die cutting of the individual labels. In such operations, ithas generally been necessary to releasably adhere the printed web to acarrier sheet so as to permit die cutting of the labels. Once the labelsare cut, the matrix is removed from the carrier, leaving the labelsspaced on the carrier sheet which was then formed into a roll. Carriersheets of this type typically represent nearly one half of the materialcost of label production. This is a tremendous waste of resources, andthe spent carrier sheets also present an on-going trash disposal burden.

[0006] In response to these problems, it has been suggested in the pastto employ laser cutting devices in lieu of traditional die cuttingsystems. Moreover, some laser cutting systems are “linerless” in thatthe use of carrier sheets is eliminated. For example, U.S. Pat. No.5,681,412 describes a modem-day laser cutting label production system ofthis type.

[0007] While such laser systems are a significant advance in the art,some problems remain. For example, the upstream printing of label stockprior to laser cutting has not heretofore been seriously addressed inprior laser-based systems. That is, traditional printing methods, bethey either web fed multiple-tower printers or even conventional digitalprinting equipment, it is usually necessary to employ relatively thickwebs having sufficient mechanical strength to withstand the printingoperation. Rollers or other devices used to pull the webs through theseprinting units impose significant stresses on the webs, and if the websare too thin or otherwise insufficiently strong, the webs have atendency to break. As a consequence, it has generally been necessary toemploy web having a thickness of at least about 2 mils. These webs arerelatively expensive, as compared with thinner webs of, e.g., 0.5 milthickness.

SUMMARY OF THE INVENTION

[0008] The present invention overcomes the problems outlined above andprovides improved web printing and handling apparatus especially(although not exclusively) suitable for label making. Broadly speaking,the web printing and handling apparatus of the invention includes a webprinting assembly operable to print successive, individual images on acontinuously moving web, including a rotatable impression drumpresenting an outer surface and at least one (and usually plural)digital print head(s) adjacent the drum outer surface. A downstream webcutting and handling assembly including a laser cutter and a collectionassembly for laser cut images also forms a part of the overallapparatus. Finally, a web guidance system operable to guide a continuousweb around at least a portion of the drum surface and between the drumsurface and print head(s) is provided, allowing printing of successiveimages on the web. In practice, with the apparatus of the invention usecan be made of relatively thin, inexpensive webs. This stems from thefact that during printing, the linear speed of the web and the speed ofthe impression drum surface are closely matched so that there isessentially no relative movement between the impression drum surface andweb. Consequently, the web is stabilized during printing and is notsubjected to undue tension or other forces which would otherwise distortor break the web. By the same token, use of digital print heads andassociated sensors permits very accurate registration printing so thathigh quality images can be produced on demand.

[0009] In preferred forms, the print head maybe inkjet or laser printhead, or any other suitable digitally-controlled printing device. Theimpression drum is preferably rotatable in opposite directions asdesired, so that either side of a web may be printed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic representation of the improved web printingand handling apparatus of the invention, particularly designed for theon-demand production of labels;

[0011]FIG. 2 is a view similar to that of FIG. 1, but illustrating theapparatus with reverse travel of the continuous web, as compared withFIG. 1; and

[0012]FIG. 3 is a schematic representation similar to that of FIG. 2,but depicting the use of a pair of serially related printing impressiondrums.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] Turning now to the drawings, and particularly FIG. 1, a webprinting and handling apparatus 10 is illustrated in a configurationespecially adapted for the production of product labels. The apparatus10 includes a printing assembly 12 and a downstream web cutting andhandling assembly 14. The apparatus 10 is designed to accept acontinuous web 16 and to print a succession of individual images (e.g.,labels) on the web 16, followed by cutting and storage of the cutimages. A feature of the invention is the use of a digital printingassembly and a relatively large impression drum, thereby permitting useof lightweight, thin, relatively low cost webs.

[0014] In more detail, the printing assembly 12 includes a relativelylarge (at least about 3 feet in diameter and more preferably from about4-6 feet in diameter) impression drum 18 presenting an outer surface 20.The drum 18 is mounted for controlled rotation in either direction,i.e., clockwise or counterclockwise, by means of servo-driven gearlesselectronic drives (in this context “gearless” refers to the fact thatthe drum 18 does not have a peripheral gear as is common with typicalgear train-driven drums). Thus (see FIG. 1), the drum 18 is rotatable ona central shaft 19 which is coupled with a servo-drive 19 a.Furthermore, the drum is provided with internal passageways for coolingmedia such s chilled water or the like. The overall assembly 12 furtherincludes at least one, and preferably a plurality of digital print heads22. As shown in FIG. 1, a total of eight print heads 22 a-22 h areprovided in circumferentially spaced relationship about and adjacent tosurface 20 of drum 18. The print heads 22 can be any one of a number ofdigitally operated devices, such as inkjet, electrophotographic, iondeposition, electrographic, magnetophotographic, direct thermal, thermaltransfer, digital, offset or laser printing heads. It will beappreciated that each such print head is individually driven andelectronically controlled, which may include a servo-drive if needed.

[0015] In preferred practice, most of print heads 22 have an associatedphotosensor 24, in the case of FIG. 1, sensors 24 a-24 g. Similarly, theprint heads have adjacent UV or EB (electron beam) curing devices 26, asshown in FIG. 1, the devices 26 a-26 f. Finally, it will be observedthat additional UV/EB curing devices 28 and 30 are located about theperiphery of drum 18.

[0016] The web cutting and handling assembly 14 includes a digitallyoperated adhesive application device 32, which can provide eithersequential application of the adhesive or flood-coating as desired. Arotatable chill roller 34 is located downstream of device 32, and has anopposed UV/EB curing device 36. A scanning camera (typically a DDCcamera) 38 is located downstream of the chill roller 34. Similarly, aconventional laser cutter 40 is disposed downstream of the roller 34 buton the opposite side of web 16. A vacuum and chill roller 42 is orienteddownstream of the camera 38 and laser cutter 40.

[0017] The assembly 14 also includes a cut image collection assembly 44adjacent roller 42. The assembly 44 has an unwind roller 46 and a takeuproller 48; a liner web 50 is supported between the rollers 46, 48, andis trained about an intermediate nip-forming roller 52 which forms a cutimage transfer nip with roller 42 as shown. An optional EAS (electronicarticle surveillance) device 54 is positioned just upstream of the niproller 52 and is operable to apply or print an RFID tag or otheridentifying indicia to cut labels. A sensor 55 associated with device 54is employed to insure that the EAS tags are applied only to properly cutlabels.

[0018] The overall printing assembly 12 further includes a web guidancesystem 56 which is operable to guide web 16 around at least a portion ofdrum surface 20 and between the latter and print head(s) 22 for printingof the outer face of web 16 with a succession of images; the system 56also serves to guide the printed web into and through the assembly 14.In detail, the guidance system 56 includes a pair of alternate unwindrollers 58 and 60 (see FIG. 2), a support roller 62, and a pair of servorollers 64, 66 located on opposite sides of the drum 18. An infeed niproller 68 is positioned adjacent servo roller 64 and forms, with surface20, an infeed nip with web 16. In like manner, an exit nip roller 70 islocated adjacent servo 66, and forms with surface 20 an exit nip for web16. In preferred practice, the system 56 also includes one or moreadditional support rollers 72, photosensor 74 and an additional,optionally usable, heatable laminating roller 76. Finally, the system 56includes a matrix nip roller 78 adjacent and upstream of device 54,together with a matrix web takeup roller 80.

[0019] Although not shown in detail, it will be appreciated that theoperation of apparatus 10 is microprocessor-controlled. That is, thesensors 24 and 74, camera 38, print heads 22, curing devices 24, 28 and30, device 32, laser cuter 40 and the drum 18 and rollers 34 and 42 areall operatively coupled with microprocessor(s). Such microprocessoroperation is controlled via known software, such as that commercializedby Wave Front Technologies of Irvine, Calif.

[0020] As indicated previously, the apparatus 10 illustrated in FIG. 1is particularly suited for the production of labels. Accordingly, in theensuing discussion, the operation of apparatus 10 for label productionwill be explained; it should be understood, however, that the apparatus10 may be used in production of other printed articles if desired.

[0021] In the course of preparing labels using the apparatus 10, astarting web roll is mounted on unwind roller 58 and is threaded aroundrollers 62, 64 and 68, and about the surface 20 of drum 18. The web isfurther trained around rollers 70 and 66, and over rollers 72 and 76.Finally, the web is trained about nip roller 78 for ultimate takeup onmatrix takeup roller 80. During printing and processing operation, thedrum 18 is rotated at a predetermined speed and the web guidance 56 isoperated to likewise move the web 16 around the drum 18 and through theremainder of the apparatus 10. In this connection, it is desired thatthe speed of drum surface 20 be essentially equal to the linear speed ofthe web 16, i.e., there is essentially no relative movement between thesurface 20 and web 16 between the nip rollers 68, 70. This is insuredthrough control of the rotational speed of drum 18, and control of webspeed via system 56. In the latter case, the servo-rollers 64, 66provide on-the-go tension and speed control of the web 16.

[0022] As the web 16 traverses the web surface 20 between the niprollers 68, 70, the print heads 22 a-22 h are operated to individuallyprint label images onto the outer surface of the web. As will be readilyunderstood, each of the heads can be designed for printing a respectivecolor so that the final printed images may be multi-colored to anydesired extent. The operation of the print heads is controlled via thesensors 24. In the usual practice, web 16 is provided with fiducials orother eye marks adjacent or associated with the image-bearing regions ofthe web, and these are sensed by the sensors 24 so as to insure properregistration between the printing performed by each of the printingheads. In order to provide the highest quality printing, the individualcuring devices 26 and 28, 30 are also operated during rotation of drum18. This serves to at least partially dry and cure images or partsthereof deposited by the respective digital print heads 22.

[0023] As the web 16 leaves drum 18, it has printed thereon the desired,spaced label images. The web then traverses the rollers 72, 76 withintermediate sensing by sensor 74. Next, the web enters assembly 14 andis adhesively coated by device 32. In this connection, a feature of theinvention is the ability to print on a face of the web 16 and then applyadhesive over the printing. This serves to “bury” the image so as toproduce a higher quality label. As indicated previously, device 32,under microprocessor control, can be used to apply adhesive only toregions of the label images, or alternately, the web surface may beflood-coated.

[0024] After application of adhesive, the web 16 proceeds through astation defined by chill roller 34 and opposed curing device 36. Thisserves to fully cure and dry the adhesive applied upstream by the device32.

[0025] Next, the printed label images are scanned by camera 38 so as toinsure that they are all of appropriate quality. All such approvedimages are next laser cut using the cutter 40. This produces a series ofindividual labels 82 which are picked up by the vacuum operation ofroller 42 for conveyance to nip roller 52. At the same time, the uncutremainder of the web 16, in the form of a matrix 16 a, is taken up bytakeup roller 80.

[0026] The individual labels 82 carried by roller 42 proceed to the areaof nip roller 52 where such labels are collected on the liner 50. Inparticular, it will be observed that the liner 50, proceeding fromunwind roller 46, around nip roller 50 and onto takeup roller 48, ispositioned so as to accept and collect the individual labels 82. As eachlabel 82 comes to a point adjacent the nip defined by nip roller 52 androller 42, the vacuum holding the respective label 82 to the surface ofroller 42 is relieved, thereby allowing the label to be picked up by theliner 50. As a consequence, the liner 50, with the applied labels 82, isrolled up to form a salable label product.

[0027] In the event that one or more label images of inferior qualityare detected by camera 38, the microprocessor controller signals lasercutter 40 to not cut such inferior label images. Therefore, suchinferior images form a part of the matrix web 16 a and are collected ontakeup roller 80 along with the cut matrix. In this way, the apparatus10 avoids collection of substantial labels on collection liner 50. Also,the sensor 55 comes into play with respect to such uncut labels, inorder to prevent application of an EAS device thereon.

[0028]FIG. 2 depicts an apparatus 84 very similar to apparatus 10 andincluding a printing assembly 12 and a web cutting and handling assembly14. For ease of discussion, like components will be similarly numberedbetween FIGS. 1 and 2. In the FIG. 2 embodiment, the web 16 is mountedon alternate unwind roller 60 and thus proceeds in an opposite directionabout surface 20 of drum 18 as compared with the FIG. 1 embodiment. Bythe same token, in the FIG. 2 embodiment, the drum 18 is rotated in aclockwise direction, as compared with the counter-clockwise direction ofFIG. 1. Use of the alternate unwind roller 60 allows the opposite sideof web 16 to be printed, as compared with the FIG. 1 embodiment. Also asshown in FIG. 2, a laminating web 86 may be applied to the printed faceof web 16 prior to entrance of the composite into the assembly 14. Tothis end, the web 86 is mounted on primary unwind roller 58 and isapplied to web 16 by heating of laminating roller 76.

[0029] The operation of apparatus 84 proceeds in exactly the samefashion as that described with reference to FIG. 1, with the exceptionof the described reverse travel of web 16 and the application oflaminating web 86 to the printed face of web 16.

[0030]FIG. 3 illustrates a still further apparatus 88 in accordance withthe invention, which is very similar to that shown in FIG. 2. However,in this case, an additional printing drum 90 with associated print heads22, sensors 24, and UV/EB curing devices 26 is provided in the web path,prior to entrance of the web into the cutting and handling assembly 14.The purpose of the additional drum 90 and associated devices is topermit high speed operation through greater printing capacity. Also, theadditional print heads allow further colors to be applied, as comparedwith use of only a single printing drum.

[0031] The apparatus and methods of the invention allow the user toproduce high quality labels or other images using relatively low costweb material. That is, inasmuch as the web 16 is printed whiletraversing the drum 18 (and also drum 90 in the case of FIG. 3), the webis fully stabilized during the printing operation. This stems from thefact that the speed of the web 16, and that of the drum surface, areclosely matched to essentially eliminate relative movement between thedrum and web. This is to be contrasted with conventional systems whereinthicker, sturdier webs must be employed in order to avoid web breakageduring printing or downstream handling. Furthermore, the use ofmicroprocessor-controlled digital print heads allows production of veryhigh quality printing, even at high speed, and with an on-demandfeature.

[0032] The speed of the web is consistent with the speed of the drum 18due to the web being in contact with the surface of the drum. Only asmall amount of tension is applied to the web during travel thereof pastthe digital printing stations while the web is in contact with the drum.This is in contrast with conventional in-line systems where materialwith greater internal tensile values which increase thickness and/orcost, must be employed in order to avoid web breakage or elongationduring web travel through the in-line printing and converting process.Furthermore, the use of microprocessor-controlled digital print headsallows for consisting high quality printing over a wide range of speeds.

[0033] While the foregoing embodiments depict the use of webs withadhesive application during processing, webs previously coated with acured, activatable adhesive could also be employed, thus eliminating theneed for in-line adhesive application.

We claim:
 1. A web cutting and handling apparatus comprising: anadhesive application device for applying adhesive to a continuouslymoving web having images printed thereon; an adhesive curing device; acamera located downstream of said curing device operable to scan saidimages; a laser cutter operable to selectively cut said images from saidweb thereby producing a stream of cut labels and a waste matrix; and alabel transfer assembly operable to receive and transfer said labelsonto a continuous liner.
 2. The apparatus of claim 1, said curing devicebeing a UV or electron beam curing device.
 3. The apparatus of claim 1,further comprising a chill roller positioned opposite said curingdevice.
 4. The apparatus of claim 1, including a waste matrix take-uproller.
 5. The apparatus of claim 1, including an electronic articlesurveillance device positioned downstream of said laser cutter forapplying identifying indicia to said labels.
 6. The apparatus of claim5, said surveillance device operable to apply or print an RFID tag tosaid labels.
 7. The apparatus of claim 5, further comprising a sensorproximate said surveillance device for monitoring application of saidindicia to said labels.
 8. The apparatus of claim 1, including a linerunwind roller, a liner takeup roller, and a nip roller locatedtherebetween, said rollers operable to guide said liner during transferof said labels to said liner.
 9. The apparatus of claim 1, said labeltransfer assembly comprising a vacuum roller.
 10. A method of handling aweb having images printed thereon comprising the steps of: providing anadhesive application device; guiding said web past said adhesiveapplication device and applying adhesive thereto; curing said adhesiveon said web; scanning said images after said adhesive curing step todetermine the quality of each individual image; cutting said images fromsaid web using a laser cutting device thereby producing a stream oflabels and a waste matrix; providing a label transfer assembly proximatesaid laser cutting device for receiving said labels; and transferringsaid labels onto a continuous liner.
 11. The method of claim 10, saidadhesive application step comprising sequentially applying adhesive overat least a portion of said images.
 12. The method of claim 10, saidcuring step comprising guiding said web through a curing station definedby a chill roller and an opposed curing device.
 13. The method of claim12, said curing device selected from a member of the group consisting ofUV and electron beam curing devices.
 14. The method of claim 10,selectively cutting said images from said web based on the result ofsaid scanning step with any uncut images being taken up as a part ofsaid waste matrix.
 15. The method of claim 10, including the step ofapplying to said labels an identifying indicia.
 16. The method of claim15, said identifying indicia being an RFID tag.
 17. The method of claim10, said label transfer assembly comprising a vacuum roller.